Insulin resistance is a common metabolic dysfunction that can lead to various chronic illnesses, including type 2 diabetes, cardiovascular disease, and obesity. Evidence suggests that at least 25% of adults in the United States who don't have diabetes are insulin-resistant.
Insulin resistance occurs when the body's cells fail to respond to insulin. This causes more insulin to be produced, leading to chronically high insulin levels.
Physical activity has been shown to help prevent insulin resistance from developing and reduce its effects once it has developed. This article will highlight the role of exercise in improving insulin sensitivity and preventing associated complications.
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What Is Insulin Resistance?
Insulin has two main functions:
- Acting as a hormone to reduce blood glucose levels.
- Acting as a signaling molecule for cells in practically every organ of the body.
Insulin resistance is a disruption of metabolism that occurs when cells of the body do not respond to insulin stimulation, both as a signaling hormone and as a hormone to lower blood sugar levels. To understand insulin resistance, it is necessary to understand the physiology of insulin.
In a healthy patient, insulin is released by the beta cells of the pancreas in response to a rise in blood glucose, which occurs after the ingestion of carbohydrates. When a patient eats carbohydrates, and the body metabolizes them, blood glucose rises.
This signals the pancreas to release insulin. Insulin then helps return blood glucose levels to the normal range by telling cells how to use the glucose—either to send it to various organs to be used as energy or to store it as fat (adipose tissue).
However, when this process is dysfunctional, insulin resistance occurs, causing blood glucose levels to remain consistently elevated and continually stimulating the pancreas to release more insulin.
Causes and Risk Factors
Many factors increase the risk of developing insulin resistance.
Obesity
Obesity is strongly associated with insulin resistance, as excess adipose tissue accumulation is a significant risk factor for developing insulin resistance.
Adipose tissue (especially visceral or abdominal fat) produces pro-inflammatory cytokines and adipokines, which disrupt insulin signaling pathways and promote insulin resistance. Furthermore, elevated levels of free fatty acids in obesity also worsen insulin resistance by impeding insulin action in peripheral tissues.
Lastly, insulin is a pro-inflammatory hormone, and obesity is a pro-inflammatory state. Obesity and insulin resistance promote energy storage instead of energy burning, which predisposes to a continuous cycle of metabolic dysfunction and weight gain.
Lifestyle Factors
Beyond obesity, these additional lifestyle factors play a significant role in developing insulin resistance.
- Diets high in processed foods, such as added sugars, refined carbohydrates, and processed meats, lead to a pro-inflammatory state, increasing the risk of insulin resistance.
- Physical inactivity or a sedentary lifestyle increases the risk of developing insulin resistance.
- Chronic stress leads to higher cortisol levels, increased appetite, and dysregulation in other metabolic hormones, predisposing to insulin resistance.
- Poor sleep leads to dysregulated cortisol and ghrelin, increasing the risk of weight gain and insulin resistance.
Genetic Predispositions
In addition to lifestyle factors, genetic predispositions also increase the risk of developing insulin resistance. Variations in genes coding for insulin signaling or other genetic factors affecting lipid metabolism, mitochondrial activity, and inflammatory mediators can increase the risk of insulin resistance.
Examples of genetic markers that increase the risk for insulin resistance include:
- PTP1B
- LEPR
- RETN
- SLC2A4
The Role of Physical Exercise in Managing Insulin Resistance
Regular physical activity, including cardiovascular exercise and strength training, is imperative to improve insulin sensitivity and maintain a healthy weight.
By increasing glucose uptake and utilization in muscles, physical exercise helps lower blood sugar levels and improve insulin sensitivity. Regular physical exercise results in more lean body mass and increases resting energy expenditure. Together, it helps promote a healthy weight and insulin sensitivity.
Benefits of Exercise
Physical activity provides a host of short-term and long-term benefits on metabolic health.
Short-Term Benefits
- Enhancing resting energy expenditure or metabolic rate
- Improving circulation to muscles and organs
- Lowering blood pressure
- Improving insulin sensitivity
- Reducing inflammation
- Lowering stress hormones
- Enhancing mood
- Increasing energy levels
Long-Term Benefits
- Long-term weight management
- Reduced risk of type 2 diabetes
- Better cardiovascular health
- Improved lipid metabolism
- Increased muscle mass and physical strength
- Improved chronic hormone regulation
- Enhanced mitochondrial function
- Lowered chronic inflammation
- Improved longevity and overall quality of life
4 Types of Exercise To Help With Your Insulin Resistance
1: Aerobic (Cardiovascular) Exercise
Cardiovascular exercise, such as fast walking, jogging, running, cycling, and swimming, enhances insulin sensitivity by increasing glucose uptake and utilization in skeletal muscles. This reduces blood glucose levels and improves insulin resistance.
Cardiovascular exercise is also known to help promote a healthy weight by boosting energy expenditure and encouraging fat burning.
2: Resistance (Strength) Training
Strength training, including bodyweight exercises and weightlifting, has been demonstrated to enhance insulin sensitivity by increasing muscle mass and glucose uptake into muscles.
Strength training is known to help increase and preserve lean body mass, supporting long-term weight management by increasing resting energy expenditure. Combining cardiovascular exercise and strength training improves insulin sensitivity, promotes weight loss, and helps maintain metabolic health.
3: High-Intensity Interval Training (HIIT)
HIIT training involves aerobic cardiovascular exercise with strength training using bodyweight exercise. It includes alternating between several minutes of high-intensity aerobic exercise that increases the heart rate to about 80% of its maximum with lower-intensity strength training. This high intensity allows for shorter workouts that can deliver results more quickly.
One meta-analysis compared HIIT to other continuous physical activity and found that after removing other confounding factors, following a HIIT training program resulted in a 1.3 kg greater weight loss and a 0.19% reduction in hemoglobin A1c (HbA1c).
A randomized controlled trial found that HIIT improved several markers of insulin sensitivity and glucose metabolism.
4: Yoga
Yoga has been shown to improve glycemic control, including lower fasting blood glucose, postprandial blood sugar, HbA1c, fasting insulin levels, and HOMA-IR.
Another study showed significant improvements in lipid profiles and reduced adverse cardiovascular events in patients with type 2 diabetes mellitus. Yoga's additional benefits include reducing stress and improving mental health, which can also help promote insulin sensitivity.
How To Implement Exercise Into Your Lifestyle
Creating an Effective Exercise Plan
Implementing regular exercise requires first creating an effective exercise plan. By evaluating individual health factors and current health conditions, such as joint pain, muscle weakness, fatigue, cardiovascular health, and glycemic control, your healthcare provider can help formulate a safe and effective personalized exercise plan for your lifestyle.
This should include gradual increases in activity level and duration of exercise as tolerated, with ongoing reassessments and modifications as necessary.
Overcoming Common Barriers to Exercise
Changing behavior in the long term takes time, consistency, motivation, and commitment. Implementing regular exercise requires overcoming inevitable obstacles.
- Time can be a significant obstacle for many patients. By planning ahead, you can schedule exercise around other commitments.
- Motivation can wax and wane over time. An individualized plan should emphasize doable activities that are also enjoyable, encouraging adherence to the exercise plan.
- Consistency and commitment are reinforced by tracking progress, adjusting goals over time, and sticking to a personalized plan for the best outcomes.
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Key Takeaways
- Insulin resistance is a multifaceted metabolic dysfunction that increases the risk of chronic illnesses, including obesity, type 2 diabetes, cardiovascular disease, metabolic syndrome, and more.
- Many factors predispose to insulin resistance, such as lifestyle and genetic factors, and optimizing many of these factors can also mitigate the effects of insulin resistance.
- Improving diet, managing stress, and improving sleep will all improve insulin resistance.
- Implementing regular physical activity has been shown to prevent and treat insulin resistance.
- Regular physical activity also has many other short-term and long-term benefits for overall health.
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